Knocking normal?

370zFORme!!

Ok so, Ive been searching online and on this forum unsuccessfully for answers, I'm hoping someone can shed some light on this for me. I know this topic has been beaten to death about what oil is best for engine knocking, but I have not found my answer yet. Since I purchased my 370z about 3 weeks ago, I've been hearing a slight engine knocking. Almost sounds like a lifter tap. Ive had my first oil change done and they used Nissan Ester oil. They say its normal, but you never know with the dealer these days. I was under the impression from other posts that supposedly Nissan Ester oil helps with these knocking noises. In my situation it has not.

Couple things:
1. Is knocking normal on our cars?
2. Are there any safe additives out there for reducing engine knocking?
3. Anyone else had good experiences with noise reduction after switching to an Ester based full synthetic like Redline, or Motul?

Sorry if these are silly questions, but this being the first $30000+ car I've ever purchased, I'm a little paranoid about excessive engine noise. Any suggestions are appreciated in advance!